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#41
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Speakers testing
"Svante" wrote in message om... It should not be THAT hard to add the two signals, given that phase and amplitude is taken into account. Of course that depends on what you mean with "near field"; if the microphone is put VERY close to the membrane/port, then the effective distance (ie the amplitude) may be hard to estimate correctly. On the other hand, the "inside-the-box" method elegantly adds up the two volume flows automatically. Only at very low frequencies. Phase cancellation of multiple driver systems usually occurs at frequencies higher than can be measured using the "inside box" method. But remember you do not need a half wavelength for *some* cancellation to take place. TonyP. |
#42
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Speakers testing
"Svante" wrote in message om... It should not be THAT hard to add the two signals, given that phase and amplitude is taken into account. Of course that depends on what you mean with "near field"; if the microphone is put VERY close to the membrane/port, then the effective distance (ie the amplitude) may be hard to estimate correctly. On the other hand, the "inside-the-box" method elegantly adds up the two volume flows automatically. Only at very low frequencies. Phase cancellation of multiple driver systems usually occurs at frequencies higher than can be measured using the "inside box" method. But remember you do not need a half wavelength for *some* cancellation to take place. TonyP. |
#43
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Speakers testing
"Svante" wrote in message om... It should not be THAT hard to add the two signals, given that phase and amplitude is taken into account. Of course that depends on what you mean with "near field"; if the microphone is put VERY close to the membrane/port, then the effective distance (ie the amplitude) may be hard to estimate correctly. On the other hand, the "inside-the-box" method elegantly adds up the two volume flows automatically. Only at very low frequencies. Phase cancellation of multiple driver systems usually occurs at frequencies higher than can be measured using the "inside box" method. But remember you do not need a half wavelength for *some* cancellation to take place. TonyP. |
#44
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Speakers testing
"Tony Pearce" wrote in message . au...
"Svante" wrote in message om... It should not be THAT hard to add the two signals, given that phase and amplitude is taken into account. Of course that depends on what you mean with "near field"; if the microphone is put VERY close to the membrane/port, then the effective distance (ie the amplitude) may be hard to estimate correctly. On the other hand, the "inside-the-box" method elegantly adds up the two volume flows automatically. Only at very low frequencies. Phase cancellation of multiple driver systems usually occurs at frequencies higher than can be measured using the "inside box" method. But remember you do not need a half wavelength for *some* cancellation to take place. Agree, we were talking about different frequency ranges here. I was referring to the addition of the port and the woofer in a bass-reflex system, this should not be VERY hard. Adding the sounds from a woofer and a tweeter would be a completely different matter, given the higher frequency at the crossover. And of course, the inside-the-box cannot provide such an addition. |
#45
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Speakers testing
"Tony Pearce" wrote in message . au...
"Svante" wrote in message om... It should not be THAT hard to add the two signals, given that phase and amplitude is taken into account. Of course that depends on what you mean with "near field"; if the microphone is put VERY close to the membrane/port, then the effective distance (ie the amplitude) may be hard to estimate correctly. On the other hand, the "inside-the-box" method elegantly adds up the two volume flows automatically. Only at very low frequencies. Phase cancellation of multiple driver systems usually occurs at frequencies higher than can be measured using the "inside box" method. But remember you do not need a half wavelength for *some* cancellation to take place. Agree, we were talking about different frequency ranges here. I was referring to the addition of the port and the woofer in a bass-reflex system, this should not be VERY hard. Adding the sounds from a woofer and a tweeter would be a completely different matter, given the higher frequency at the crossover. And of course, the inside-the-box cannot provide such an addition. |
#46
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Speakers testing
"Tony Pearce" wrote in message . au...
"Svante" wrote in message om... It should not be THAT hard to add the two signals, given that phase and amplitude is taken into account. Of course that depends on what you mean with "near field"; if the microphone is put VERY close to the membrane/port, then the effective distance (ie the amplitude) may be hard to estimate correctly. On the other hand, the "inside-the-box" method elegantly adds up the two volume flows automatically. Only at very low frequencies. Phase cancellation of multiple driver systems usually occurs at frequencies higher than can be measured using the "inside box" method. But remember you do not need a half wavelength for *some* cancellation to take place. Agree, we were talking about different frequency ranges here. I was referring to the addition of the port and the woofer in a bass-reflex system, this should not be VERY hard. Adding the sounds from a woofer and a tweeter would be a completely different matter, given the higher frequency at the crossover. And of course, the inside-the-box cannot provide such an addition. |
#47
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Speakers testing
"Svante" wrote in message om... Agree, we were talking about different frequency ranges here. I was referring to the addition of the port and the woofer in a bass-reflex system, this should not be VERY hard. Adding the sounds from a woofer and a tweeter would be a completely different matter, given the higher frequency at the crossover. And of course, the inside-the-box cannot provide such an addition. You still miss the point I was making. The tweeter frequencies can be easily measured using MLS gating systems. The problem is with multi - woofer systems eg. D'Appolito designs commonly available these days. Near field measurements are made on one woofer, then MLS measurements are made for high frequencies. If the room height is small as it usually is, then errors will occur when combining near field measurements at frequencies lower than can be gated. TonyP. |
#48
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Speakers testing
"Svante" wrote in message om... Agree, we were talking about different frequency ranges here. I was referring to the addition of the port and the woofer in a bass-reflex system, this should not be VERY hard. Adding the sounds from a woofer and a tweeter would be a completely different matter, given the higher frequency at the crossover. And of course, the inside-the-box cannot provide such an addition. You still miss the point I was making. The tweeter frequencies can be easily measured using MLS gating systems. The problem is with multi - woofer systems eg. D'Appolito designs commonly available these days. Near field measurements are made on one woofer, then MLS measurements are made for high frequencies. If the room height is small as it usually is, then errors will occur when combining near field measurements at frequencies lower than can be gated. TonyP. |
#49
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Speakers testing
"Svante" wrote in message om... Agree, we were talking about different frequency ranges here. I was referring to the addition of the port and the woofer in a bass-reflex system, this should not be VERY hard. Adding the sounds from a woofer and a tweeter would be a completely different matter, given the higher frequency at the crossover. And of course, the inside-the-box cannot provide such an addition. You still miss the point I was making. The tweeter frequencies can be easily measured using MLS gating systems. The problem is with multi - woofer systems eg. D'Appolito designs commonly available these days. Near field measurements are made on one woofer, then MLS measurements are made for high frequencies. If the room height is small as it usually is, then errors will occur when combining near field measurements at frequencies lower than can be gated. TonyP. |
#50
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Speakers testing
"Tony Pearce" wrote in message . au...
"Svante" wrote in message om... Agree, we were talking about different frequency ranges here. I was referring to the addition of the port and the woofer in a bass-reflex system, this should not be VERY hard. Adding the sounds from a woofer and a tweeter would be a completely different matter, given the higher frequency at the crossover. And of course, the inside-the-box cannot provide such an addition. You still miss the point I was making. The tweeter frequencies can be easily measured using MLS gating systems. The problem is with multi - woofer systems eg. D'Appolito designs commonly available these days. Near field measurements are made on one woofer, then MLS measurements are made for high frequencies. If the room height is small as it usually is, then errors will occur when combining near field measurements at frequencies lower than can be gated. Hmm, in that case I still fail to understand what you mean. Could you enlighten me on what a D'Appolito design is (I must confess I don't know). Are you speaking about a closed box or bass-reflex. I realise that the time between direct sound and the first reflection will determine the lowest frequency that can be used when gating an impulse response, but I fail to see why this would make combination of this and near-field measurement hard. Do you mean that it would force us to use the near-field measurement at a too high frequency? |
#51
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Speakers testing
"Tony Pearce" wrote in message . au...
"Svante" wrote in message om... Agree, we were talking about different frequency ranges here. I was referring to the addition of the port and the woofer in a bass-reflex system, this should not be VERY hard. Adding the sounds from a woofer and a tweeter would be a completely different matter, given the higher frequency at the crossover. And of course, the inside-the-box cannot provide such an addition. You still miss the point I was making. The tweeter frequencies can be easily measured using MLS gating systems. The problem is with multi - woofer systems eg. D'Appolito designs commonly available these days. Near field measurements are made on one woofer, then MLS measurements are made for high frequencies. If the room height is small as it usually is, then errors will occur when combining near field measurements at frequencies lower than can be gated. Hmm, in that case I still fail to understand what you mean. Could you enlighten me on what a D'Appolito design is (I must confess I don't know). Are you speaking about a closed box or bass-reflex. I realise that the time between direct sound and the first reflection will determine the lowest frequency that can be used when gating an impulse response, but I fail to see why this would make combination of this and near-field measurement hard. Do you mean that it would force us to use the near-field measurement at a too high frequency? |
#52
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Speakers testing
"Tony Pearce" wrote in message . au...
"Svante" wrote in message om... Agree, we were talking about different frequency ranges here. I was referring to the addition of the port and the woofer in a bass-reflex system, this should not be VERY hard. Adding the sounds from a woofer and a tweeter would be a completely different matter, given the higher frequency at the crossover. And of course, the inside-the-box cannot provide such an addition. You still miss the point I was making. The tweeter frequencies can be easily measured using MLS gating systems. The problem is with multi - woofer systems eg. D'Appolito designs commonly available these days. Near field measurements are made on one woofer, then MLS measurements are made for high frequencies. If the room height is small as it usually is, then errors will occur when combining near field measurements at frequencies lower than can be gated. Hmm, in that case I still fail to understand what you mean. Could you enlighten me on what a D'Appolito design is (I must confess I don't know). Are you speaking about a closed box or bass-reflex. I realise that the time between direct sound and the first reflection will determine the lowest frequency that can be used when gating an impulse response, but I fail to see why this would make combination of this and near-field measurement hard. Do you mean that it would force us to use the near-field measurement at a too high frequency? |
#53
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Speakers testing
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#54
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Speakers testing
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#57
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Speakers testing
(Stewart Pinkerton) wrote in message ...
On 18 Dec 2003 09:57:24 -0800, (Svante) wrote: "Tony Pearce" wrote in message . au... Hmm, in that case I still fail to understand what you mean. Could you enlighten me on what a D'Appolito design is (I must confess I don't know). It's a vertical array with twin bass/mids and a third-order crossover, and it's noted for a very smooth vertical dispersion pattern around the crossover frequency. Many such 'WTW' designs are around today, but not all are true d'Appolito arrays. Many are so-called '2.5 way' designs, which are conventional single bass/mid designs at the tweeter crossover point. Invented by audio legend Joe d'Apollito, hence the name. Are the two bass/mid speakers identical? Do they both play the same frequency range? If not, how does the filter look, that manages to arrange that? I was thinking the other day about something like this for the bass/mid part of the speaker: ---------- | Speaker 1 | *---------- | | Speaker 2 Capacitor | | ----------*---------- I think that this network would give a straight frequency response if the drivers have a flat response. At low frequencies both would play, total power from the amplifier would be halved due to the doubled impedance, but efficiency would be doubled due to the dual drivers so the net gain would be =1. At high frequencies, only speaker 1 would play, but the amplifier would deliver full power. The benefit from this arrangement would be improved maximum acoustic output at low frequencies, but the less directed radiation of a single speaker at higher frequencies. Is this what is done, combined with a standard third order crossover filter in the d'Appolito design? |
#58
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Speakers testing
(Stewart Pinkerton) wrote in message ...
On 18 Dec 2003 09:57:24 -0800, (Svante) wrote: "Tony Pearce" wrote in message . au... Hmm, in that case I still fail to understand what you mean. Could you enlighten me on what a D'Appolito design is (I must confess I don't know). It's a vertical array with twin bass/mids and a third-order crossover, and it's noted for a very smooth vertical dispersion pattern around the crossover frequency. Many such 'WTW' designs are around today, but not all are true d'Appolito arrays. Many are so-called '2.5 way' designs, which are conventional single bass/mid designs at the tweeter crossover point. Invented by audio legend Joe d'Apollito, hence the name. Are the two bass/mid speakers identical? Do they both play the same frequency range? If not, how does the filter look, that manages to arrange that? I was thinking the other day about something like this for the bass/mid part of the speaker: ---------- | Speaker 1 | *---------- | | Speaker 2 Capacitor | | ----------*---------- I think that this network would give a straight frequency response if the drivers have a flat response. At low frequencies both would play, total power from the amplifier would be halved due to the doubled impedance, but efficiency would be doubled due to the dual drivers so the net gain would be =1. At high frequencies, only speaker 1 would play, but the amplifier would deliver full power. The benefit from this arrangement would be improved maximum acoustic output at low frequencies, but the less directed radiation of a single speaker at higher frequencies. Is this what is done, combined with a standard third order crossover filter in the d'Appolito design? |
#59
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#61
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Speakers testing
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#62
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Speakers testing
Lionel wrote in message news:bs09lc$faq$1@news-
I thought that "d" was MidBass center to MidBass center distance in a MTM configuration (Midbass - Tweeter - Midbass). ------- 0 Midbass | | | d |------- o tweeter | | | ------- 0 Midbass d = (sound speed / Xover frequency) example for a Xover fz of 1500 hz : sound speed = 331m/s d = 331 / 1500 = 0.22m = 8.66" Could you please confirm. Yes, one wavelength at 1500 Hz is about 8.7 in. (depends on the temperature of the air) I did a Google search for "D'appolito". I couldn't find his original 1983 paper, but I did find some references to it. The references placed the midbass drivers at 2 W.L. apart. It looks like Ray Alden was correct. Bob Stanton |
#63
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Speakers testing
Lionel wrote in message news:bs09lc$faq$1@news-
I thought that "d" was MidBass center to MidBass center distance in a MTM configuration (Midbass - Tweeter - Midbass). ------- 0 Midbass | | | d |------- o tweeter | | | ------- 0 Midbass d = (sound speed / Xover frequency) example for a Xover fz of 1500 hz : sound speed = 331m/s d = 331 / 1500 = 0.22m = 8.66" Could you please confirm. Yes, one wavelength at 1500 Hz is about 8.7 in. (depends on the temperature of the air) I did a Google search for "D'appolito". I couldn't find his original 1983 paper, but I did find some references to it. The references placed the midbass drivers at 2 W.L. apart. It looks like Ray Alden was correct. Bob Stanton |
#64
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Speakers testing
Lionel wrote in message news:bs09lc$faq$1@news-
I thought that "d" was MidBass center to MidBass center distance in a MTM configuration (Midbass - Tweeter - Midbass). ------- 0 Midbass | | | d |------- o tweeter | | | ------- 0 Midbass d = (sound speed / Xover frequency) example for a Xover fz of 1500 hz : sound speed = 331m/s d = 331 / 1500 = 0.22m = 8.66" Could you please confirm. Yes, one wavelength at 1500 Hz is about 8.7 in. (depends on the temperature of the air) I did a Google search for "D'appolito". I couldn't find his original 1983 paper, but I did find some references to it. The references placed the midbass drivers at 2 W.L. apart. It looks like Ray Alden was correct. Bob Stanton |
#65
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Speakers testing
(Bob-Stanton) wrote in message m...
(Svante) wrote in message Hmm, in that case I still fail to understand what you mean. Could you enlighten me on what a D'Appolito design is (I must confess I don't know). Are you speaking about a closed box or bass-reflex. From "Advanced Speaker Systems" by Ray Alden: "In his 1983 paper, "A Geometric Approach to Elimination Lobing Errors in Multiway Loudspeakers," Dr. Joseph D'Appolito found a way to create Ahh, that seems interesting! Would you know where this article was published? JAES? Does the book give a reference? |
#66
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Speakers testing
(Bob-Stanton) wrote in message m...
(Svante) wrote in message Hmm, in that case I still fail to understand what you mean. Could you enlighten me on what a D'Appolito design is (I must confess I don't know). Are you speaking about a closed box or bass-reflex. From "Advanced Speaker Systems" by Ray Alden: "In his 1983 paper, "A Geometric Approach to Elimination Lobing Errors in Multiway Loudspeakers," Dr. Joseph D'Appolito found a way to create Ahh, that seems interesting! Would you know where this article was published? JAES? Does the book give a reference? |
#67
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Speakers testing
(Bob-Stanton) wrote in message m...
(Svante) wrote in message Hmm, in that case I still fail to understand what you mean. Could you enlighten me on what a D'Appolito design is (I must confess I don't know). Are you speaking about a closed box or bass-reflex. From "Advanced Speaker Systems" by Ray Alden: "In his 1983 paper, "A Geometric Approach to Elimination Lobing Errors in Multiway Loudspeakers," Dr. Joseph D'Appolito found a way to create Ahh, that seems interesting! Would you know where this article was published? JAES? Does the book give a reference? |
#71
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Speakers testing
(Bob-Stanton) wrote in message . com...
(Svante) wrote in message . com... From "Advanced Speaker Systems" by Ray Alden: "In his 1983 paper, "A Geometric Approach to Elimination Lobing Errors in Multiway Loudspeakers," Dr. Joseph D'Appolito found a way to create Ahh, that seems interesting! Would you know where this article was published? JAES? Does the book give a reference? ? ? :-( Errh.. I mean, I don't have the book, but it seems as if the book might refer to a scientific paper (from 1983) or similar. My guess was that it was published in Journal of Audio Engineering Society (JAES), but that is of course a guess. Books often have a reference list and I wondered if you could look there to see where this 1983 paper was published? |
#72
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Speakers testing
(Bob-Stanton) wrote in message . com...
(Svante) wrote in message . com... From "Advanced Speaker Systems" by Ray Alden: "In his 1983 paper, "A Geometric Approach to Elimination Lobing Errors in Multiway Loudspeakers," Dr. Joseph D'Appolito found a way to create Ahh, that seems interesting! Would you know where this article was published? JAES? Does the book give a reference? ? ? :-( Errh.. I mean, I don't have the book, but it seems as if the book might refer to a scientific paper (from 1983) or similar. My guess was that it was published in Journal of Audio Engineering Society (JAES), but that is of course a guess. Books often have a reference list and I wondered if you could look there to see where this 1983 paper was published? |
#73
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Speakers testing
(Bob-Stanton) wrote in message . com...
(Svante) wrote in message . com... From "Advanced Speaker Systems" by Ray Alden: "In his 1983 paper, "A Geometric Approach to Elimination Lobing Errors in Multiway Loudspeakers," Dr. Joseph D'Appolito found a way to create Ahh, that seems interesting! Would you know where this article was published? JAES? Does the book give a reference? ? ? :-( Errh.. I mean, I don't have the book, but it seems as if the book might refer to a scientific paper (from 1983) or similar. My guess was that it was published in Journal of Audio Engineering Society (JAES), but that is of course a guess. Books often have a reference list and I wondered if you could look there to see where this 1983 paper was published? |
#74
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Speakers testing
(Svante) wrote in message om...
(Bob-Stanton) wrote in message . com... (Svante) wrote in message . com... From "Advanced Speaker Systems" by Ray Alden: Errh.. I mean, I don't have the book, but it seems as if the book might refer to a scientific paper (from 1983) or similar. My guess was that it was published in Journal of Audio Engineering Society (JAES), but that is of course a guess. Books often have a reference list and I wondered if you could look there to see where this 1983 paper was published? I found it. :-) Speaker Builder, published by Audio Amateur Press P.O.box 494, Peterborough, NH, 03458-0494 Telephone: 800 -524-9464 "Back issues are available." "A High Powered Satellite Speaker", by Joseph D'Appolito, Issue 4/1984 Bob Stanton |
#75
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Speakers testing
(Svante) wrote in message om...
(Bob-Stanton) wrote in message . com... (Svante) wrote in message . com... From "Advanced Speaker Systems" by Ray Alden: Errh.. I mean, I don't have the book, but it seems as if the book might refer to a scientific paper (from 1983) or similar. My guess was that it was published in Journal of Audio Engineering Society (JAES), but that is of course a guess. Books often have a reference list and I wondered if you could look there to see where this 1983 paper was published? I found it. :-) Speaker Builder, published by Audio Amateur Press P.O.box 494, Peterborough, NH, 03458-0494 Telephone: 800 -524-9464 "Back issues are available." "A High Powered Satellite Speaker", by Joseph D'Appolito, Issue 4/1984 Bob Stanton |
#76
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Speakers testing
(Svante) wrote in message om...
(Bob-Stanton) wrote in message . com... (Svante) wrote in message . com... From "Advanced Speaker Systems" by Ray Alden: Errh.. I mean, I don't have the book, but it seems as if the book might refer to a scientific paper (from 1983) or similar. My guess was that it was published in Journal of Audio Engineering Society (JAES), but that is of course a guess. Books often have a reference list and I wondered if you could look there to see where this 1983 paper was published? I found it. :-) Speaker Builder, published by Audio Amateur Press P.O.box 494, Peterborough, NH, 03458-0494 Telephone: 800 -524-9464 "Back issues are available." "A High Powered Satellite Speaker", by Joseph D'Appolito, Issue 4/1984 Bob Stanton |
#77
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Speakers testing
(Bob-Stanton) wrote in message . com...
(Svante) wrote in message om... (Bob-Stanton) wrote in message . com... (Svante) wrote in message . com... From "Advanced Speaker Systems" by Ray Alden: Errh.. I mean, I don't have the book, but it seems as if the book might refer to a scientific paper (from 1983) or similar. My guess was that it was published in Journal of Audio Engineering Society (JAES), but that is of course a guess. Books often have a reference list and I wondered if you could look there to see where this 1983 paper was published? I found it. :-) Speaker Builder, published by Audio Amateur Press P.O.box 494, Peterborough, NH, 03458-0494 Telephone: 800 -524-9464 "Back issues are available." "A High Powered Satellite Speaker", by Joseph D'Appolito, Issue 4/1984 Bob Stanton OK, it was not what I hoped for (I don't have that book), but thanks anyway! |
#78
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Speakers testing
(Bob-Stanton) wrote in message . com...
(Svante) wrote in message om... (Bob-Stanton) wrote in message . com... (Svante) wrote in message . com... From "Advanced Speaker Systems" by Ray Alden: Errh.. I mean, I don't have the book, but it seems as if the book might refer to a scientific paper (from 1983) or similar. My guess was that it was published in Journal of Audio Engineering Society (JAES), but that is of course a guess. Books often have a reference list and I wondered if you could look there to see where this 1983 paper was published? I found it. :-) Speaker Builder, published by Audio Amateur Press P.O.box 494, Peterborough, NH, 03458-0494 Telephone: 800 -524-9464 "Back issues are available." "A High Powered Satellite Speaker", by Joseph D'Appolito, Issue 4/1984 Bob Stanton OK, it was not what I hoped for (I don't have that book), but thanks anyway! |
#79
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Speakers testing
(Bob-Stanton) wrote in message . com...
(Svante) wrote in message om... (Bob-Stanton) wrote in message . com... (Svante) wrote in message . com... From "Advanced Speaker Systems" by Ray Alden: Errh.. I mean, I don't have the book, but it seems as if the book might refer to a scientific paper (from 1983) or similar. My guess was that it was published in Journal of Audio Engineering Society (JAES), but that is of course a guess. Books often have a reference list and I wondered if you could look there to see where this 1983 paper was published? I found it. :-) Speaker Builder, published by Audio Amateur Press P.O.box 494, Peterborough, NH, 03458-0494 Telephone: 800 -524-9464 "Back issues are available." "A High Powered Satellite Speaker", by Joseph D'Appolito, Issue 4/1984 Bob Stanton OK, it was not what I hoped for (I don't have that book), but thanks anyway! |
#80
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